Temporary web support for wind turbine blade rotating device

ABSTRACT

Provided herein is a shear web support for wind turbine blade. Particularly, the present disclosure provides a frangible shear web support element that is designed to fail under certain specific conditions. The frangible support(s) enhance the structural rigidity of the shear web, allow for one-step mold closures, and rupture or disconnect once a predetermined condition (e.g. load threshold, load orientation/vector) is applied to the support element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 USC 119 of priority to U.S.Provisional Application No. 62/729,502 filed Sep. 11, 2018, the entirecontents of which are hereby incorporated by reference.

BACKGROUND OF THE DISCLOSED SUBJECT MATTER Field of the DisclosedSubject Matter

The disclosed subject matter relates to a system, and correspondingmethod, of manufacturing large scale composite structures, e.g. windturbine blades. These large scale composite structures are typicallyformed from a two-piece mold which, once the blade halves are molded,require a complex mold closure process to complete fabrication.

Particularly, the present disclosure provides structural elements whichfacilitate a one-step mold closure technique by employing a supportelement to maintain the web to be substantially free standing within amold half.

Description of Related Art

Wind turbine blades generally comprise a hollow blade shell madeprimarily of composite materials, such as glass-fiber reinforcedplastic. The blade shell is typically made up of two half shells, alower pressure-side shell and an upper suction-side shell, which aremolded separately in respective female half molds, before being bondedtogether along flanges at the leading and trailing edges of the blade.This method of manufacturing a blade is illustrated schematically inFIG. 1 a.

Referring to FIG. 1 a, this shows a mold 10 for a wind turbine bladedivided into two half molds, an upper suction-side mold 10 a and a lowerpressure-side mold 10 b, which are arranged side by side in an openconfiguration of the mold. A pressure side blade shell 12 a is supportedon a mold surface 14 a of the lower mold 10 a and a suction side bladeshell 12 b is supported on a mold surface 14 b of the upper mold 10 b.The shells 12 a, 12 b are each made up of a plurality of glass-fiberfabric layers, which are bonded together by cured resin.

After forming the shells 12 a, 12 b in the respective mold halves 10 a,10 b, shear webs 16 are bonded to an inner surface 17 of the windwardblade shell 12 a. The shear webs 16 are longitudinally-extendingstructures that bridge the two half shells 12 a, 12 b of the blade andserve to transfer shear loads from the blade to the wind turbine hub inuse. In cross-section, as shown in FIG. 1 a, the shear webs 16 eachcomprise a web 18 having a lower edge 19 comprising a firstlongitudinally-extending mounting flange 20 and an upper edge 21comprising a second longitudinally-extending mounting flange 22.Adhesive such as epoxy is applied along these mounting flanges 22 inorder to bond the shear webs 16 to the respective half shells 12 a, 12b.

As shown in FIG. 1 b, once the shear webs 16 have been bonded to theupper blade shell 12 a, adhesive is applied along the second (upper)mounting flanges 22 of the shear webs 16, and along the leading edge 24and trailing edge 26 of the blade shells 12 a, 12 b. The upper mold 10b, including the upper blade shell 12 b, is then lifted, turned andplaced on top of the lower blade mold 10 a in order to bond the twoblade half shells 12 a, 12 b together along the leading and trailingedges 24, 26 and to bond the shear webs 16 to an inner surface 28 of theupper blade shell 12 b. The step of placing one mold half on top of theother is referred to as closing the mold.

Referring now to FIG. 1C, a problem can arise when the mold 10 is closedwhereby the shear webs 16 may move slightly relative to the upper shell12 b. For example, the shear webs 16 may move slightly under their ownweight during mold closing or they may be dislodged by contact with theupper shell 12 b. The concave curvature of the upper shell 12 b also hasa tendency to force the shear webs 16 together slightly, as shown inFIG. 1C. Such movement of the shear webs 16 during mold closing mayresult in the shear webs 16 being bonded to the upper shell 12 b at asub-optimal position.

Furthermore, there are various techniques which require employingpermanent fixtures to guide the shear webs during mold closure. Anexample of which is provided in U.S. Patent Publication No.2017/0151711, the contents of which are hereby incorporated in itsentirety, including the web guide structures. However, use of suchpermanent fixtures adversely impact the blade weight, as well asincreasing design complexity and costs, impacting the designed structureof the blade by becoming parasitic to blade structure in use. Moreover,the prior methods had to be part of the initial blade design

There thus remains a need for an efficient and economic method andsystem for providing support for the webs/structure elements during theassembly phase of wind turbine devices that ensure proper placement ofthe shear web and facilitate a one-step mold closure, without impactingthe structure of the product.

Accordingly, in order to close a blade in a one-step process, the blademust be designed to be built with freestanding structural elements tosupport a one-step close, or additional structural elements must beadded to provide support. In accordance with the present disclosure,supports are frangible, i.e., designed to fail under certain specificconditions. These supports can be made of multiple materials orcombinations of materials to facilitate the assembly of the wind blade.

SUMMARY OF THE DISCLOSED SUBJECT MATTER

The purpose and advantages of the disclosed subject matter will be setforth in and apparent from the description that follows, as well as willbe learned by practice of the disclosed subject matter. Additionaladvantages of the disclosed subject matter will be realized and attainedby the methods and systems particularly pointed out in the writtendescription and claims hereof, as well as from the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the disclosed subject matter, as embodied and broadly described, thedisclosed subject matter includes an apparatus, comprising a blade,including first and second spar caps; a first wall coupled to the firstspar cap; a second wall coupled to the second spar cap; a shear webcoupled to at least the first spar cap; and a frangible support coupledto the shear web and the first wall, wherein the frangible support isconfigured to fail under a predefined condition.

In some embodiments, the frangible support includes a first leg and asecond leg, with a frangible connection disposed therebetween. In someembodiments, the predefined condition is a stress threshold amount. Insome embodiments, the predefined condition is a load vector, e.g. theload vector is oriented orthogonally to a longitudinal axis of thesupport. In some embodiments, the frangible portion is located at amidpoint of the support, includes a weakened section, includes a pullcord, and/or is oriented at approximately 45 degrees relative to theshear web. In some embodiments, a plurality of frangible support membersare provided with at least two frangible support members spacedapproximately 12.5 meters apart.

In accordance with another aspect of the disclosure, a method ofassembling a wind turbine blade is provided which comprises: providing afirst blade half; providing a second blade half; providing a shear web,the shear web coupled to the first blade half; coupling a frangiblesupport to the shear web and the first blade half; and triggering thefrangible support to fail.

In some embodiments, triggering the frangible support to fail includespulling a cord to disengage a frangible connecting portion from theremainder of the support. In some embodiments, triggering the frangiblesupport to fail includes applying a stress in excess of a thresholdamount. In some embodiments, triggering the frangible support to failincludes applying a load along a vector oriented at an angle to thelongitudinal axis of the support. In some embodiments, triggering thefrangible support to fail includes positioning the second blade half ontop of the first blade half. In some embodiments, the method furthercomprises removing the frangible support from the assembled blade.

In some embodiments, the frangible support is oriented at approximately45 degrees relative to the shear web. In some embodiments, the frangiblesupport is coupled to the shear web at approximately the midpoint of theshear web. In some embodiments, the method further comprises providing aplurality of frangible support members, at least two frangible supportmembers spaced approximately 12.5 meters apart. In some embodiments, themethod further comprises providing a second frangible support member,and coupling the second frangible support to the shear web and thesecond blade half.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and are intended toprovide further explanation of the disclosed subject matter claimed.

The accompanying drawings, which are incorporated in and constitute partof this specification, are included to illustrate and provide a furtherunderstanding of the method and system of the disclosed subject matter.Together with the description, the drawings serve to explain theprinciples of the disclosed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of various aspects, features, and embodiments ofthe subject matter described herein is provided with reference to theaccompanying drawings, which are briefly described below. The drawingsare illustrative and are not necessarily drawn to scale, with somecomponents and features being exaggerated for clarity. The drawingsillustrate various aspects and features of the present subject matterand may illustrate one or more embodiment(s) or example(s) of thepresent subject matter in whole or in part.

FIGS. 1A-C depict cross-sectional views of a conventional wind turbineblade mold and manufacturing method.

FIG. 2 is a cross-section of a blade with a frangible support inaccordance with an embodiment of the present disclosure.

FIG. 3 is cross-section of a blade with a frangible support in a secondstate in accordance with an embodiment of the present disclosure.

FIG. 4 is a cross-section of a blade with multiple frangible supports inplace in accordance with an embodiment of the present disclosure.

FIG. 5 is cross-section of a blade with a frangible support with a pullcord/cable for triggering failure/release of the frangible connection,in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

Reference will now be made in detail to exemplary embodiments of thedisclosed subject matter, an example of which is illustrated in theaccompanying drawings. The method and corresponding steps of thedisclosed subject matter will be described in conjunction with thedetailed description of the system.

The methods and systems presented herein may be used for large structureconstruction. The disclosed subject matter is particularly suited forconstruction of wind turbine blades. For purpose of explanation andillustration, and not limitation, an exemplary embodiment of the systemin accordance with the disclosed subject matter is shown in FIG. 2 andis designated generally by reference character 100. Similar referencenumerals (differentiated by the leading numeral) may be provided amongthe various views and Figures presented herein to denote functionallycorresponding, but not necessarily identical structures.

As shown in FIG. 2, shear web 115 is bonded on the upper end (or suctionside) to spar cap 105. In the embodiment shown, the blade skin 130 canextend between the web 115 and the spar cap 105 such that an inner/lowersurface of the spar cap 105 is bonded to, or integral with, the bladeskin. An upper surface of the web 115 can be bonded to the inner surfaceof the blade skin 130. Similarly, the opposite end of shear web 115 isbonded to spar cap 125 on the lower (or pressure side) such that aninner/upper surface of the spar cap 125 is bonded to, or integral with,the blade skin 135, and a lower surface of the web 120 can be bonded tothe inner surface of the blade skin 135.

In some embodiments the spar caps can be formed as discrete elementswhich are coupled to the blade skin 130, 135. In other embodiments, thespar caps are formed as components which are woven or blended into theblade skin so as to form an integral coupling. For example, the spar cap105 can be incorporated during the molding process into the blade shellsuch that a skin ply extends across the spar cap (on both the inside ofthe shell and the outer surface of the shell). The shear web 115, andcorresponding spar caps 105, 125, extend longitudinally along the bladespan.

Although only a single shear web 115 is depicted in the exemplaryembodiment, additional shear webs can be employed within the scope ofthe present disclosure. Furthermore, although the shear web 115 isdepicted as an I-beam construction, alternative shear web configurationscan be employed, e.g. split beams having generally a U-shape or V-shapeconstruction, if so desired.

In some embodiments, shear web 115 is mounted to internal wall 130 usingmount 110. Mount 110 is attached to internal wall 130 using a structuraladhesive. Likewise, web 115 can be mounted to internal wall 135 usingmount 120. Mount 120 is attached to internal wall 135 using a structuraladhesive. In various embodiments, a structural adhesive may need to cureto completely adhere to a structure.

In accordance with an aspect of the disclosure, shear web 115 issupported by support 165. Support 165 includes mount 140, mount 160, afirst reinforcing leg 45, second reinforcing leg 155, and connectionportion 150.

Connecting portion 150 is a frangible section configured to “fail” underspecific conditions, as shown in FIG. 3. That is, support 165 contains afrangible element/section, which is designed to “fail” (e.g. sever,rupture, detach, transform, etc.) under a load that is different thanthe load the support is meant to carry when performing the function ofmaintaining the position of the shear web 115 in the blade during thetime the adhesive (bond paste) cures.

In some embodiments the triggering event which causes the connectingportion 150 to fail is a predetermined load threshold (which can bequantified in terms of stress/strain exhibited on the support 165).Additionally or alternatively, the triggering event which causes theconnecting portion 150 to fail can be the load vector (e.g. a loadapplied along an improper direction/vector). Additionally oralternatively, the triggering event which causes the connecting portion150 to fail can be a release mechanism which breaks the load transferpath through support 165. For example, the release mechanism can be arelease lever which displaces connecting portion 150 relative to legs145, 165. In some embodiments the release mechanism can be a cord/cablewhich attaches (e.g. via releasable pin) to connecting portion 150 andextends outside of the blade mold (including when both upper and lowerhalves are assembled) and allows for an operator to pull (e.g.laterally) which could “break” the support 165 (even though it hasadequate strength to support the shear web in position when loaded alongthe axis of legs 145 and 155).

Support 165 is mounted to the web 115 and lower skin 135 using mount 140and mount 160, respectively. Mount 140 is attached to web 115 using afast setting adhesive. Mount 160 is attached to internal wall 135 usinga fast setting adhesive. In some embodiments the mounts 140, 160 can berigidly attached to the legs 145, 155. In other embodiments the mounts140, 160 can be coupled to the legs 145, 155 to permit relative movementbetween the legs/mounts. For example, the mounts 140, 160 can bepivotably attached (e.g. via hinges, ball joint, etc.) so that the mountcan rotate to conform to any contour that may be present in the innersurfaces of the blade skins. In the exemplary embodiment depicted, thesupport 165 is configured such that mount 160 is spaced from spar cap125 (i.e. is attached to the skin at a location adjacent to the spar cap125). In some embodiments, the mount 160 can be located, partially orentirely, above the spar cap 125.

The support 165 can be coupled to the shear web 115 at a wide range ofangles (with respect to the longitudinal/vertical axis of the web 115).In the exemplary embodiment shown, the angle is approximately a 45degrees. However, this angle can be adjusted as desired such that insome embodiments (e.g., ones incorporating a heavier shear web 115), theangle between the web 115 and support 165 is smaller, therebytransferring a larger component of the weight of the web 115 through thesupport 165. Conversely, the angle between the web 115 and support 165can be increased, resulting in a support 165 which provides more lateralsupport and stability to prevent or inhibit any undesired lateralshifting of the web 115 (but receiving less of the vertical load fromthe web 115).

Additionally, the connection points for mounts 140, 160 can influencethe angle of the support 165 with respect to the web 115. In someembodiments a minimum height relative to the height of the shear web canbe prescribed. For example, in some embodiments the angle of support 165can be dictated/defined in terms of mount locations, with the mount 140at a position no less than approximately 25% of the height of the shearweb 115 and no more than approximately 75% of the height of the shearweb 115. In some embodiments the angle of support 165 may be no lessthan 30 degrees and no more than 60 degrees.

Additionally, or alternatively, a plurality of supports 165 can beemployed at select locations along the blade span. In some embodiments,the supports 165 are equidistant from each other. In other embodimentsthe supports 165 can be arranged with varied density/concentration alongthe blade span so as to provide greater support in a certain region(e.g. root) of the blade than in others (e.g. tip). Also, the supportscan be provided on only a single side of the shear web 115, as shown, oralternatively can be located on both sides of the web 115.

In accordance with an aspect of the disclosure, the use of as fewsupports 165 as possible is desired—while ensuring the positionaltolerance of the shear web is maintained during the cure time. In someembodiments, a minimum of three supports 165 are provided—located atroot end, mid-span and within 12.5 m of tip end. In some embodiments,the minimum number of supports 165 required is the number to span thelength of the shear web with a maximum spacing of 12.5 m with supportslocated at the root end of the shear web and within 12.5 m of the tipend of the shear web.

As shown in FIG. 3, the frangible connecting portion 150 failed, asdesigned, at the location shown by arrow 205. As a result, any loadapplied to the shear web 115 is absorbed/transferred entirely throughthe web. The designed failure of support 165 has removed the structuralsupport and therefore any impedance to the movement of the shear web115. In other words, the support 165 provides enhanced rigidity andsupport to prevent or inhibit displacement of the shear web, until thefrangible connecting section 150 fails, which results in a free standingshear web 115. In the embodiments shown, the frangible portion 150 islocated at a midpoint of the support 165. However, the frangible portioncan be located at the connection point of either of, or both, mounts140,160 or any location therebetween.

FIG. 4 is a simplified illustration of an alternate embodiment of afrangible support within a system, in accordance with an embodiment ofthe present disclosure. System 300 includes spar 305, mount 310, web315, mount 320, spar 325, internal skins 330, 335. In this embodiments,system 300 includes two frangible supports, frangible support 340 andfrangible support 345. As shown, the frangible portion 340 does notcomprise an alternate or distinct geometry from the remainder of thesupport 345. This can be achieved, for example, by providing thefrangible portion which is inherently weaker, via a difference inmaterial composition, from the remainder of the support 345, asdescribed below. When a specified amount of stress is placed on system300, the frangible supports 340, 345 shall fail, as designed, allowingfor the support to be readily removed from the final blade construction.

The frangible section can be formed in a variety of ways. For example,the support can be formed with a weakened section (e.g. notch, scoringor perforation) that yields once the force applied reaches apredetermined threshold. In some embodiments, the frangible section caninclude a phase change material (e.g. paraffin or a eutectic) that losesrigidity, e.g. melts upon application of a catalyst.

Additionally or alternatively, the support can be formed with variedmaterial properties, e.g. non-homogenous composition along the supportlength, such that the frangible section yields once a predeterminedcondition is realized. The predetermined condition can be a load amount,localized temperature, or via application of a material (e.g.acid/enzyme) that deteriorates the structural integrity of the frangibleportion. In some embodiments, the frangibility threshold can be a resultof a load applied in a direction (or plane) orthogonal to the primaryload orientation carried by the supports 340, 345. In such embodiments,the strength of the frangible element can be greater than the loadrequired (applied in an orthogonal plane) to break the support 340, 345after the shear web has been bonded in place. For purpose ofillustration and not limitation, an exemplary load required to fracturethe frangible element can be less than 25 kgs.

In some embodiments, the support (including the frangible portion(s))can be formed with sufficient structural integrity and strength towithstand all forces applied during the assembly process, andsubsequently fail/fracture as a result of loads carried by operation ofthe blade in the field. Variable wind loading causes deflection of theblade thereby imparting loads on the frangible element of the supportcausing fracture. The required force to fail the support can be greaterthan the load required to perform the function of the supporting theshear web, but not so large that the performance of the blade isaffected by the internal stiffness of the support before the frangibleelement fails.

In some embodiments the frangible section is made of a foam (e.g.polyurethane), with the remainder of the support webs 145, 155 formed ofa more rigid and permanent material, e.g. metal or wood. Additionally oralternatively, the supports can be made of fiberglass.

In some embodiments, the frangible portion does not “break” or becomedetached from the remainder of the support 165. For example, thefrangible portion can include a hinge or latch which can be actuated todisconnect from the remainder of the support. In such embodiments, thefrangible portion merely disconnects or severs the transfer of anyforces within the support, but does not actually become physicallydecoupled from the remainder of the support.

According to an aspect of the disclosure, the current system provides ashear web structural support element that: i) provides enhanced rigidityand structural support to the shear web during blade assembly; ii)facilitates a one-step closure of the mold halves in a system that isfree from external (to the blade) fixtures; and iii) is removable uponclosure of the mold halves to result in a blade that is free of residualor non-essential blade structures.

In operation, adhesive is applied along the leading and trailing edgesof the respective half shells and along the longitudinally-extendingflanges of the shear webs. Next, the first mold halve (e.g. the upper orsuction side mold half) is then lifted, turned 180 degrees and placed ontop of the other mold half. As the mold closes, any force applied to theshear web(s) are guided through the support element 165, which maintainsthe web 115 in an orientation that is substantially perpendicular to thelocal surface of the mold (and blade skin). Consequently, no shearforces are applied to the shear web(s) during mold closure. The absenceof shear forces being applied allows for squeezing of the adhesive toensure that a strong bond is created between the shear webs and theblade skin. As the upper blade half is placed on top of the shear web115, the weight of the blade is gradually released to a point where theload being transmitted through the web 115 and support 165 reaches thepredetermined threshold of frangible section 150 to rupture ordisconnect the frangible portion. Additionally or alternatively, thefrangible section(s) can be manually triggered to fail e.g. via a pullcord/cable 200, as shown in FIG. 5. After which, the entire load of theupper blade half is transmitted through the web 115.

In accordance with another aspect of the present disclosure, thesupport(s) 165, once the frangible portion is broken or deconstructed,does not transmit any force applied to the shear web 115. Furthermore,the support 165 can be removed from the interior of the blade. Thus, thefinal blade assembly does not impart any undesired weight, or influencethe structural characteristics of the blade. As a result, the bladeperformance characteristics remain unchanged when in use in a windturbine system. For example, the support 165 components, after thefrangible section(s) has failed, can be removed from inside the blade bypulling them out through the root section (which remains open afterassembly of the two mold halves).

In various embodiments, a web or structural element support can includea frangible portion. A frangible portion may be designed to fail undercertain specific conditions to remove any structural impact of the webor structural element support on the final blade construction when thefrangible portion has failed per design. In various embodiments, afrangible feature and/or portion can be the result of specificgeometries of the frangible feature and/or portion. A frangible portionmay be constructed and/or configured from a specific material designedto fail or change state under predetermined conditions. The methods andsystems of the disclosed subject matter, as described above and shown inthe drawings, provide for an efficient and economic system for providingsupport for the webs/structure elements during the assembly phase, e.g.mold closure, of wind turbine blades without impacting the structure ofthe blade.

While the disclosed subject matter is described herein in terms ofcertain preferred embodiments, those skilled in the art will recognizethat various modifications and improvements may be made to the disclosedsubject matter without departing from the scope thereof. Moreover,although individual features of one embodiment of the disclosed subjectmatter may be discussed herein or shown in the drawings of the oneembodiment and not in other embodiments, it should be apparent thatindividual features of one embodiment may be combined with one or morefeatures of another embodiment or features from a plurality ofembodiments.

In addition to the specific embodiments claimed below, the disclosedsubject matter is also directed to other embodiments having any otherpossible combination of the dependent features claimed below and thosedisclosed above. As such, the particular features presented in thedependent claims and disclosed above can be combined with each other inother manners within the scope of the disclosed subject matter such thatthe disclosed subject matter should be recognized as also specificallydirected to other embodiments having any other possible combinations.Thus, the foregoing description of specific embodiments of the disclosedsubject matter has been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit thedisclosed subject matter to those embodiments disclosed.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the method and system of thedisclosed subject matter without departing from the spirit or scope ofthe disclosed subject matter. Thus, it is intended that the disclosedsubject matter include modifications and variations that are within thescope of the appended claims and their equivalents.

1. An apparatus, comprising: a blade, comprising: a first and secondspar cap; a first wall, wherein the first wall is coupled to the firstspar cap; a second wall, wherein the second wall is coupled to thesecond spar cap; a shear web coupled to at least the first spar cap; anda frangible support coupled to the shear web and the first wall, whereinthe frangible support is configured to fail under a predefinedcondition.
 2. The apparatus of claim 1, wherein the frangible supportincludes a first leg and a second leg, with a frangible connectiondisposed therebetween.
 3. The apparatus of claim 1, wherein thepredefined condition is a stress threshold amount.
 4. The apparatus ofclaim 1, wherein the predefined condition is a load vector.
 5. Theapparatus of claim 4, wherein the load vector is oriented orthogonallyto a longitudinal axis of the support.
 6. The apparatus of claim 1,wherein the frangible portion is located at a midpoint of the support.7. The apparatus of claim 1, wherein the frangible portion includes aweakened section.
 8. The apparatus of claim 1, wherein the frangibleportion includes a pull cord.
 9. The apparatus of claim 1, wherein thefrangible support is oriented at approximately 45 degrees relative tothe shear web.
 10. The apparatus of claim 1, further comprising aplurality of frangible support members, at least two frangible supportmembers spaced approximately 12.5 meters apart.
 11. A method ofassembling a wind turbine blade comprising: providing a first bladehalf; providing a second blade half; providing a shear web, the shearweb coupled to the first blade half; coupling a frangible support to theshear web and the first blade half; triggering the frangible support tofail.
 12. The method of claim 11, wherein triggering the frangiblesupport to fail includes pulling a cord to disengage a frangibleconnecting portion from the remainder of the support.
 13. The method ofclaim 11, wherein triggering the frangible support to fail includesapplying a stress in excess of a threshold amount.
 14. The method ofclaim 11, wherein triggering the frangible support to fail includesapplying a load along a vector oriented at an angle to the longitudinalaxis of the support.
 15. The method of claim 11, wherein triggering thefrangible support to fail includes positioning the second blade half ontop of the first blade half.
 16. The method of claim 11, furthercomprising removing the frangible support from the assembled blade. 17.The method of claim 11, wherein the frangible support is oriented atapproximately 45 degrees relative to the shear web.
 18. The method ofclaim 11, wherein the frangible support is coupled to the shear web atapproximately the midpoint of the shear web.
 19. The method of claim 11,further comprising providing a plurality of frangible support members,at least two frangible support members spaced approximately 12.5 metersapart.
 20. The method of claim 11, further comprising providing a secondfrangible support member, and coupling the second frangible support tothe shear web and the second blade half.